The invention relates generally to a technique for monitoring a weld operation, and more particularly, to monitoring a quality level of a weld during the weld operation.
Various types of welding operations are known and are in use. For example, two or more metal sheets may be welded by a spot welding operation. Spot welding utilizes a spot welding machine that includes two copper electrodes held in jaws of the spot welding machine. The material to be welded is clamped between the two electrodes. Typically, a pressure may be applied to hold the electrodes together and a flow of electric current is introduced through the electrodes and the material. Further, the resistance of the material being welded is substantially higher than that of the electrodes. As a result, enough heat is being generated to melt the metal. The pressure on the electrodes forces the molten spots in the two pieces of metal to unite and this pressure is held to facilitate the solidification of the metal. It is desirable to determine the quality of the weld generated through the weld operation to ensure the structural integrity of the welded systems such as automotive frames.
Unfortunately, the present weld monitoring techniques are ineffective to determine the weld quality during the weld operation. In certain systems, excess spot welds are installed in components to ensure the structural integrity of the welded system. Such redundant welds lead to relatively higher process time and additional costs for the manufacturers. Further, excess welds in the system also increase the possibility for corrosion zones on the final product.
In certain systems, destructive testing may be employed to determine the quality of the weld. Typically, the materials joined by the weld process are separated by a hammer and a chisel to assess the strength of the weld and of the material surrounding the weld. Moreover, such destructive testing may be performed on a periodic basis to determine the quality of the weld process. Such testing is relatively time consuming and also leads to material waste.
In certain other systems, offline ultrasonic systems have been used to provide an indication of the weld quality. However, these systems provide an inspection of the weld quality after the process is completed and the weld nugget has solidified. Such systems do not provide information about the weld quality during the weld operation. Further, the existing ultrasonic systems may require a relatively large time for inspecting the weld quality of all welds of a component.
Accordingly, it would be desirable to develop a technique for monitoring the weld operation. More specifically, it would be desirable to develop a technique for real-time monitoring of the quality of the weld created during the weld operation process.